Distribution Characteristics of Pea Gravel Behind Segment in Shield Tunnel Boring Machine Tunnels

Pea gravel plays a crucial role in segment stability as the connecting layer between the segment and the surrounding rock in TBM tunnels. Due to the influence of construction technology and geological conditions, the phenomena of dense filling and uneven distribution of pea gravel often occur, leadi...

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Main Authors: Shengzhi WU, Honghai ZHAO, Hongqiang XIE, Yucang DONG, Lin FANG, Mingnian WANG, Yue LIU
Format: Article
Language:English
Published: Editorial Department of Journal of Sichuan University (Engineering Science Edition) 2024-07-01
Series:工程科学与技术
Subjects:
Online Access:http://jsuese.scu.edu.cn/thesisDetails#10.15961/j.jsuese.202201182
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author Shengzhi WU
Honghai ZHAO
Hongqiang XIE
Yucang DONG
Lin FANG
Mingnian WANG
Yue LIU
author_facet Shengzhi WU
Honghai ZHAO
Hongqiang XIE
Yucang DONG
Lin FANG
Mingnian WANG
Yue LIU
author_sort Shengzhi WU
collection DOAJ
description Pea gravel plays a crucial role in segment stability as the connecting layer between the segment and the surrounding rock in TBM tunnels. Due to the influence of construction technology and geological conditions, the phenomena of dense filling and uneven distribution of pea gravel often occur, leading to various disasters such as dislocation, cracking, and water leakage. The distribution characteristics of pea gravel behind the segment ring form the basis for analyzing segment stress. Within the context of the Qingdao metro TBM tunnel project, geological radar is employed to examine the distribution characteristics of pea gravel behind the segment wall. Subsequently, a numerical simulation of single-ring pea gravel filling is conducted. This study analyzes the migration process of pea gravel behind the segment wall in both straight and curved sections of the tunnel and discusses the impact of geological conditions, filling pressure, collapses, and other factors on the quality of the filling. The results indicated that during TBM tunnel construction, the arch crown, tunnel bottom, and lower part of the outer side of the line’s turning section are the areas most prone to pea gravel empty tunnels. Moreover, the pea gravel empty of the arch crown and tunnel bottom exceeds 1 m, while those at the lower part of the outer side of the turning section are smaller and less dense. Poorer geological conditions increase the probability and scale of voids in the pea gravel behind the segment, with strongly weathered strata showing the most significant effects. Collapses impact pea gravel reclamation by obstructing migration paths and increasing energy demands, although their impact is limited to the collapse site. Enhancing the hydraulic fill pressure of the pea gravel can improve the fill quality at the vault and tunnel bottom; the improvement is more pronounced under better geological conditions, though it does not significantly enhance the filling quality in strongly weathered strata. Based on the causes of formation, the pea gravel cavities behind the segment ring are categorized into three types: collision energy dissipation, collapse block, and smaller clearance in the turning section. Additionally, the study presents the frequent parts, characteristics, and construction recommendations related to these activities.
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publishDate 2024-07-01
publisher Editorial Department of Journal of Sichuan University (Engineering Science Edition)
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series 工程科学与技术
spelling doaj-art-6dd9fb3a172d4f7da9f63ff773eba7d72025-08-20T02:47:32ZengEditorial Department of Journal of Sichuan University (Engineering Science Edition)工程科学与技术2096-32462024-07-015615016055277696Distribution Characteristics of Pea Gravel Behind Segment in Shield Tunnel Boring Machine TunnelsShengzhi WUHonghai ZHAOHongqiang XIEYucang DONGLin FANGMingnian WANGYue LIUPea gravel plays a crucial role in segment stability as the connecting layer between the segment and the surrounding rock in TBM tunnels. Due to the influence of construction technology and geological conditions, the phenomena of dense filling and uneven distribution of pea gravel often occur, leading to various disasters such as dislocation, cracking, and water leakage. The distribution characteristics of pea gravel behind the segment ring form the basis for analyzing segment stress. Within the context of the Qingdao metro TBM tunnel project, geological radar is employed to examine the distribution characteristics of pea gravel behind the segment wall. Subsequently, a numerical simulation of single-ring pea gravel filling is conducted. This study analyzes the migration process of pea gravel behind the segment wall in both straight and curved sections of the tunnel and discusses the impact of geological conditions, filling pressure, collapses, and other factors on the quality of the filling. The results indicated that during TBM tunnel construction, the arch crown, tunnel bottom, and lower part of the outer side of the line’s turning section are the areas most prone to pea gravel empty tunnels. Moreover, the pea gravel empty of the arch crown and tunnel bottom exceeds 1 m, while those at the lower part of the outer side of the turning section are smaller and less dense. Poorer geological conditions increase the probability and scale of voids in the pea gravel behind the segment, with strongly weathered strata showing the most significant effects. Collapses impact pea gravel reclamation by obstructing migration paths and increasing energy demands, although their impact is limited to the collapse site. Enhancing the hydraulic fill pressure of the pea gravel can improve the fill quality at the vault and tunnel bottom; the improvement is more pronounced under better geological conditions, though it does not significantly enhance the filling quality in strongly weathered strata. Based on the causes of formation, the pea gravel cavities behind the segment ring are categorized into three types: collision energy dissipation, collapse block, and smaller clearance in the turning section. Additionally, the study presents the frequent parts, characteristics, and construction recommendations related to these activities.http://jsuese.scu.edu.cn/thesisDetails#10.15961/j.jsuese.202201182tunnel engineeringtunnel boring machinesegment ringpea graveldistribution characteristics
spellingShingle Shengzhi WU
Honghai ZHAO
Hongqiang XIE
Yucang DONG
Lin FANG
Mingnian WANG
Yue LIU
Distribution Characteristics of Pea Gravel Behind Segment in Shield Tunnel Boring Machine Tunnels
工程科学与技术
tunnel engineering
tunnel boring machine
segment ring
pea gravel
distribution characteristics
title Distribution Characteristics of Pea Gravel Behind Segment in Shield Tunnel Boring Machine Tunnels
title_full Distribution Characteristics of Pea Gravel Behind Segment in Shield Tunnel Boring Machine Tunnels
title_fullStr Distribution Characteristics of Pea Gravel Behind Segment in Shield Tunnel Boring Machine Tunnels
title_full_unstemmed Distribution Characteristics of Pea Gravel Behind Segment in Shield Tunnel Boring Machine Tunnels
title_short Distribution Characteristics of Pea Gravel Behind Segment in Shield Tunnel Boring Machine Tunnels
title_sort distribution characteristics of pea gravel behind segment in shield tunnel boring machine tunnels
topic tunnel engineering
tunnel boring machine
segment ring
pea gravel
distribution characteristics
url http://jsuese.scu.edu.cn/thesisDetails#10.15961/j.jsuese.202201182
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